He was a pupil of Marggraf and is known for inventing Rose's metal, a low-melting alloy of bismuth, tin and lead (melting point of 100° C, the boiling point of water!), today used as a solder. He owned the Apotheke zum weissen Schwan (White Swan Apothecary), which Klaproth joined in 1771. Rose died the same year, and Klaproth took over the care of the two sons, one of whom lived to maturity, Valentin Rose (the younger).